THK LMK30 Linear Bushing
The LMK30 is a square-flange linear bushing from THK's LMK series, designed for smooth, low-friction linear motion. Its square-flange design offers a lower core height than round-flange models, enabling more compact equipment assembly. Ideal for precision machinery, automation equipment, semiconductor manufacturing devices, and other applications requiring stable linear guidance and easy mounting.
The LMK30 is a square-flange linear bushing from THK's LMK series, designed for smooth, low-friction linear motion. Its square-flange design offers a lower core height than round-flange models, enabling more compact equipment assembly. Ideal for precision machinery, automation equipment, semiconductor manufacturing devices, and other applications requiring stable linear guidance and easy mounting.
Official Specifications
| Parameter | Value | Unit |
|---|---|---|
| Inscribed Bore Diameter (dr) | 30 | mm |
| Bore Diameter Tolerance | 0 / –0.012 | mm |
| Outer Diameter (D) | 45 | mm |
| Outer Diameter Tolerance | 0 / –0.019 | mm |
| Overall Length (L) | 64 | mm |
| Length Tolerance | ±0.3 | mm |
| Flange Diameter (D₁) | 74 | mm |
| Flange Diameter Tolerance | 0 / –0.2 | mm |
| Number of Ball Rows | 6 | — |
| Basic Dynamic Load Rating (C) | 1570 | N |
| Basic Static Load Rating (C₀) | 2750 | N |
| Mass | 375 | g |
| PCD (Mounting Hole Circle) | 60 | mm |
| Mounting Hole (d₁×d₂×h) | 6.6×11×6.5 | mm |
| Max Flange Perpendicularity | 15 | μm |
| Max Eccentricity | 15 | μm |
| Radial Clearance | Standard (–9 μm) | μm |
| Retainer Material | Synthetic Resin | — |
| Outer Sleeve Material | High-carbon Chromium Bearing Steel (SUJ2) | — |
| Ball Material | Hardened Steel | — |
| Operating Temperature Range | –10°C to +80°C | °C |
| Standard Lubrication | Pre-lubricated with anti-rust oil | — |
| Seal Type (UU Option) | Double contact seals (both ends) | — |
Key Features (Official Description)
- Square Flange Compact Design: Four-sided flattened flange for low-profile installation and space-efficient machine integration.
- High Precision & Stability: Strict dimensional tolerances ensure ultra-smooth linear motion and minimal radial clearance.
- 6-Row Ball Configuration: Provides high radial load capacity and stable operation under moderate to heavy loads.
- Resin Retainer: Lightweight, low-noise ball circulation with consistent performance.
- Easy Mounting: Direct bolting via square flange without additional fixtures; interchangeable with standard shafts.
Official Notes
- Designed exclusively for linear motion; not intended for pure rotational or moment loads.
- LMK30UU variant includes double UU seals for enhanced dust protection and lubrication retention.
- Recommended shaft: Surface hardness ≥58 HRC, surface roughness Ra ≤0.4 μm.
- Operating temperature must not exceed 80°C to prevent retainer deformation.
- Re-lubricate with lithium-based grease periodically for extended service life.
- If an oil hole is required, append "OH" to the model number (e.g., LMK30UUOH).
